Widmer G, Yang Y L, Bonilla R, Tanriverdi S, Ciociola K M
Tufts Cummings School of Veterinary Medicine, Division of Infectious Diseases, 200 Westboro Road, North Grafton, MA 01536, USA.
Parasitology. 2006 Aug;133(Pt 2):131-8. doi: 10.1017/S0031182006000151. Epub 2006 Apr 20.
In spite of its limitations, the culture of Cryptosporidium parvum in monolayers of epithelial cells is a suitable model to study the interaction of this protozoan parasite with the host cell, to assay oocyst infectivity, and to screen drugs for anti-cryptosporidial activity. For unknown reasons, growth of Cryptosporidium in culture is limited in time and generally does not lead to the production of significant numbers of oocysts. In monolayers infected with high doses of oocysts, we observed that many cells remain uninfected, suggesting that some cells are less susceptible to the infection. Since C. parvum and the related species C. hominis lack many essential biosynthetic pathways, we tested whether the dependence of the parasite on host cell metabolites may favour the infection of cells in mitosis. The proportion of monolayer cells in stationary (G0/G1) phase and in mitosis (S/G2/M) was determined and the prevalence of infected cells in each subpopulation was quantified. Although C. parvum infects and develops in dividing and stationary cells, a significant preference for cells in S/G2/M phase was observed. Consistent with previous observations showing that C. parvum induces apoptosis in cell monolayers, infection was accompanied by a significant increase in the proportion of mitotic cells.
尽管存在局限性，但利用上皮细胞单层培养微小隐孢子虫仍是一种合适的模型，可用于研究这种原生动物寄生虫与宿主细胞的相互作用、检测卵囊感染性以及筛选具有抗隐孢子虫活性的药物。由于未知原因，隐孢子虫在培养物中的生长在时间上受到限制，通常不会产生大量卵囊。在感染高剂量卵囊的单层细胞中，我们观察到许多细胞未被感染，这表明有些细胞对感染的敏感性较低。由于微小隐孢子虫及其相关物种人隐孢子虫缺乏许多必需的生物合成途径，我们测试了寄生虫对宿主细胞代谢物的依赖性是否有利于其对处于有丝分裂期的细胞的感染。我们确定了处于静止期（G0/G1期）和有丝分裂期（S/G2/M期）的单层细胞比例，并对每个亚群中感染细胞的发生率进行了量化。尽管微小隐孢子虫可在分裂期和静止期细胞中感染并发育，但我们观察到其对处于S/G2/M期的细胞有明显偏好。与之前显示微小隐孢子虫可诱导细胞单层凋亡的观察结果一致，感染伴随着有丝分裂细胞比例的显著增加。
